The use of organophosphorus-based compounds as pesticides, solvents, and plasticizers is well-known and effective in the intended capacity. However, persistence of these compounds in the environment leads to adverse collateral impact, and several known organophosphorus-based compounds are acutely toxic nerve agents to insects and humans. The adverse effects are compounded by the fact that these organophosphorus-based compounds are highly toxic even at low doses, capable of being absorbed through skin, and very fast-acting.
In particular, toxicity of organophosphorus-based compounds arises from a structural motif characterized by an electrophilic phosphorous oxide center in which the phosphorous atom is bonded to one or more, typically three, substituents, one of which is capable of acting as a leaving group. In vivo, the leaving group of the organophosphorus-based compound departs and the compound irreversibly inactivates the acetylcholinesterase (AChE) enzyme, disrupting the nervous system's ability to modulate muscular contractions. Disruption of smooth muscle tissue in the respiratory system leads to rapid death upon exposure to these toxic organophosphorus-based compounds, even at very low dosages.
Exemplary toxic organophosphorus-based compounds shown in FIGS. 1A-1E include Paraoxon (diethyl 4-nitrophenyl phosphate); VX (O-ethyl S-[2-(diisopropylamino)ethyl]methylphosphonothioate); VR (N,N-diethyl-2-(methyl-(2methylpropoxy)phosphoryl)sulfanylethanamine); Sarin gas/GB ((RS)-propan-2-yl methylphosphonofluoridate); and GF (cyclohexyl methylphosphonofluoridate). With regard to Paraoxon, the leaving group is the p-nitrophenol moiety, while for the V-series agents VX and VR, the leaving group is the 2-aminothiol moiety. Additionally, the leaving group for the G-series agents GB and GF is the fluoride ion.
Several existing techniques for inactivating or otherwise neutralizing organophosphorus-based compounds have been proposed, but generally rely on using excessive amounts of highly caustic agents such as bleach, sodium hydroxide and/or potassium hydroxide (e.g., pH≥12), which tends to damage or destroy the material to which the neutralizing agent is applied. Existing catalytic approaches rely on excessive amounts of organic solvents such as alcohols to accomplish neutralization, as well as rare and/or expensive catalysts including iridium, platinum, and/or palladium. Conventional catalytic approaches have also been troubled by a tendency for the catalyzed products to subsequently react with the catalyst, inhibiting or destroying catalytic capabilities. Particularly when using such expensive metals as catalysts, this inhibition further reduces efficiency of the overall neutralization process and exacerbates the expense of accomplishing effective neutralization. As such, the conventional techniques are expensive, and cause extensive collateral damage to the treated materials and/or the environment (e.g., where the organophosphorus-based compounds are employed as pesticides).
Accordingly, it would be of significant environmental and economic benefit to provide novel, freely available, and inexpensive materials, synthetic techniques, and deployment methods for the destruction of organophosphorus-based compounds.